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Abstract

Localized emphysema is difficult to detect on normal thoracoscopy. Indocyanine green
(ICG) was used to precisely delineate an emphysematous lesion using an infrared camera
system in a 75-year-old woman with a large emphysematous lesion in the right lower
lobe. Due to repeated infections of the emphysematous lesion, right basal segmentectomy
for localized lung emphysema was performed. During surgery, ICG (0.5 mg/kg) was injected
intravenously, and the emphysematous lesion was detected as a fluorescence defect.
This method could be used for precise resection of large emphysematous lesions because
it permits clear detection with a small amount of ICG.

Keywords:

Emphysema; VATS; Segmentectomy; Indocyanine green; Infrared camera

Background

In some cases of localized emphysema, it is difficult to detect the line between normal
lung and the emphysematous lesion. In particular, in infected lesions, accurate detection
of the line is very important to remove the entire lesion to completely eradicate
infection. An infrared camera was used to precisely delineate an emphysematous lesion
using an appropriate amount of indocyanine green (ICG). This method has already been
used in hepatectomy by injection of ICG to identify the border of a liver segment
[1] and a lung segment
[2]. The case of a patient who underwent segmentectomy for a large emphysematous lesion
using ICG detected by an infrared camera system (Photodynamic Eye: PDE-neo™, Hamamatsu
Photonics KK, Shizuoka, Japan) is reported.

Case presentation

A 75-year-old woman was referred to our department with a diagnosis of pneumonia with
a high fever. She had no significant medical history except for diabetes mellitus,
and no abnormality on screening chest X-ray had ever been detected. A computed tomography
(CT) scan showed fluid collection in a large emphysematous lesion. At first, pulmonary
sequestration of the right lower lobe was suspected, but it was eventually diagnosed
as pulmonary bullous emphysema because there was no aberrant artery from the aorta
on enhanced computed tomography. The patient was treated with antibiotics for infected
bullous emphysema. There was no clear communication between the bronchus and the bulla
on bronchoscopy, but the presence of infection suggested the possibility of a communication.
After the infection was cured, the localized emphysema had not decreased in size,
and she continued to have repeated infection in the bulla. Therefore, it was decided
that surgery to completely remove the bullous emphysematous lesion was needed. The
large bullous lesion was located by CT scan from segment 9 to segment 10 in the right
lower lobe, and it extended longitudinally to the border between segments 6 and 10
(Figure
1).

Figure 1.Chest computed tomographic images show bullous emphysema in the right lower lobe. There is no aberrant artery and no communication with the bronchus.

Video-assisted thoracoscopic surgery (VATS) was performed, and the bullous lesion
was seen both by the scope and directly by the naked eye. However, the border of the
bullous lesion was not clear in the deflated lung. ICG (0.5 mg/kg) was injected into
a right arm vein, and the lung was observed using the PDE imaging system through the
8-cm thoracotomy site. About 8 seconds after injection, ICG entered the lung, and
the bullous lesion was detected as a defect of fluorescence contrasting with the normal
lung fluorescence. The contrast remained for 30 seconds, and the ICG reached the bullous
area, which was visualized as white (Figure
2). While the contrast was present, the border between normal lung and the bullous
lesion was marked by electric cautery. During the marking, a scope from a 10-mm port
assisted in visualizing the lung because the PDE system shows a black and white view
without normal light support. It appeared that the bullous emphysematous lesion could
be resected completely by basal segmentectomy, and this was performed. There were
no complications postoperatively, and the patient was discharged 10 days postoperatively.
At follow-up 12 months after surgery, the patient had no infections and no bullous
lesions in the lung. The patient was provided informed consent to use ICG and the
Ethics Review Board on Clinical Research of Japanese Red Cross Nagasaki Genbaku Hospital
approved the study protocol (#175).

Conclusions

A localized pulmonary bulla is sometimes difficult to detect clearly on thoracoscopy,
especially in a deflated lung. VATS has already been accepted for wedge resection
of lung bullae or emphysema and partially for lobectomy or segmentectomy of lung cancer
or infectious diseases of the lung
[3,4]. Under VATS, inflation of the lung makes the operation difficult because a large
part of the chest cavity is occupied. To address this issue, Gotoh et al. used ICG
to detect bullae of pneumothorax by infrared thoracoscopy
[5]. Their infrared camera was very useful because it was a two-color infrared camera
that showed the tissue with ICG as blue and that without ICG as white. However, they
used ICG 3.0 mg/kg, which is much more than the volume of ICG used for liver function
testing
[5]. According to toxicity studies, a 5.0 mg/kg ICG intravenous injection is safe and
tolerable
[6], and another report described it as safe enough, as there were only three (0.15%)
mild adverse reactions, four (0.2%) moderate reactions, and one (0.05%) severe reaction
in 1226 consecutive patients
[7]. However, some reports noted that ICG dye has a dose-dependent toxic effect on the
retina
[8], and in our experience, prolonged vomiting or fever has occurred postoperatively
in some cases. It is clear that a smaller volume of ICG than they used is much better.

The PDE imaging system contains a charge-coupled device camera that filters out light
with a wavelength of less than 820 nm, as well as 36 light-emitting diodes with a
wavelength of 760 nm. It shows clearly that the tissue with ICG is white and that
without ICG is black
[9]. The advantage of the PDE system is high sensitivity for ICG, which allows a lower
dose of ICG (0.5 mg/kg) to be used. Since even ICG at 0.5 mg/kg can show the contrast
clearly, it may be possible to reduce the ICG dose further. Another advantage of this
approach includes the ability to see the border clearly as a black and white line
and to be able to use normal thoracoscopy from another 10-mm port to see the normal
color lung at the same time. This means that it is possible to use electrocautery
to mark the border using normal thoracoscopy and the PDE system concurrently. The
black and white contrast lasted for about 30 seconds, and then gradually the bullous
lesion turned white; this is not long, but it is enough to see the border and mark
it by electric cautery. Furthermore, because the color is lost about 15 minutes after
injection, the segment line can be used one more time during cutting. On the other
hand, a disadvantage is the large size of the system, having a diameter of 8 cm, which
requires a large incision to be used. However, in our experience, it is possible to
use at least a 4-cm incision because the part of the charged-coupled device (CCD)
camera except for the infrared light-emitting diode (LED) is 3.2 cm in diameter.

In conclusion, the procedure using the PDE system with ICG injection to perform surgery
for pulmonary bullous emphysema is safe and can be quickly completed, with minimal
drug-related side effects. This approach is cost-effective because the PDE system
can be used in other operations, and ICG is inexpensive. ICG fluorescence for lung
operations promises to be useful.

Consent

Written informed consent was obtained from the patient for publication of this Case
report and any accompanying images. A copy of the written consent is available for
review by the Editor-in-Chief of this journal.

Abbreviations

Competing interests

The authors declare that they have no competing interests.

Authors’ contribution

KM wrote the manuscript, and TN supervised the patient’s entire treatment. IS and
HT participated in the surgical operation and treatment. NY, TT, TM, and KT collected
the data and gave the PDE information. All authors read and approved the final manuscript.

Acknowledgements

The authors gratefully appreciate the support of Hamamatsu Photonics K.K., Hamamatsu,
Japan for the PDE system. There was no financial support for this study.